LE PLASMA FOCUS : INTERACTION PLASMA-COURANT ET PHÉNOMÈNES COLLECTIFS

Les phénomènes principaux de l'expérience Focus sont dûs à l'interaction d'une décharge de courant intense avec le plasma quand sont remplies les conditions de développement des instabilités microscopiques. On observe des fluctuations de densité suprathermiques, l'accélération de faisceaux d'électrons et d'ions à de hautes énergies et une résistivité anormale. Celle-ci apparaît remarquablement constante dans toute la plage d'étude, c'est-à-dire entre 20 et 2 500 kA.The main phenomena occuring in the Focus experiment are caused by the interaction of electrical current with plasma when conditions are realized for microinstabilities to develop. There is evidence of suprathermal density fluctuations, of electron and ion beams accelerated to high energies and of anomalous resistivity. The resistivity appears remarkably constant over the present range of study, between 20 and 2 500 kA

Effects of sodium chloride on the gene expression profile of periodontal ligament fibroblasts during tensile strain

Purpose During orthodontic tooth movement, pressure and tension zones develop in the periodontal ligament, and periodontal ligament fibroblasts (PDLF) become exposed to mechanical strain. Enhanced salt (NaCl) concentrations are known to modulate responses of PDLF and immune cells to different stimuli like mechanical strain. Here, we investigated the impact of tensile strain on the gene expression profile of PDLF under normal (NS) and high salt (HS) conditions. Methods After preincubation under NS or HS (+40 & x202f;mM NaCl in medium) conditions for 24 & x202f;h, PDLF were stretched 16% for 48 & x202f;h using custom-made spherical cap silicone stamps using an established and published setup. After determination of cell number and cytotoxicity, we analyzed expression of genes involved in extracellular matrix reorganization, angiogenesis, bone remodeling, and inflammation by quantitative real-time polymerase chain reaction (RT-qPCR). Results Tensile strain did not affect the expression of genes involved in angiogenesis or extracellular matrix reorganization by PDLF, which however modulate inflammatory responses and bone remodeling in reaction to 16% static tensile strain. Salt (NaCl) treatment triggered enhanced extracellular matrix formation, expression of cyclooxygenase 2 and bone metabolism in PDLF during tensile strain. Conclusions Salt (NaCl) consumption may influence orthodontic tooth movement and periodontal bone loss via modulation of extracellular matrix and bone metabolism. Excessive salt intake during orthodontic therapy may cause adverse effects regarding periodontal inflammation and bone resorption